Ive been running Trag, but its definitely boring unless youre actively breaking away from the group and just looking for elites to kill off cd. Also, since youre only useful when you have your cds up.. you arent very useful at all.. Yea you can blow up the RG but are you really worth taking over another class? If your group is fine with you blowing up maybe 5 or 6 elites and hopefully having cds up for the RG just run with that imo..
bloodmage definitely is limited.
ive tried singularity but i feel like paper.
if you are farming 80's to 90's youre gonna be slow without bloodrush.. the other dps will be carrying you. so builds without it are worthless imo if you have a mage or dh or a dps class thats fast in your group.